Installing Ruby on Shared Linux Host

Hi. I tried to follow the Howto instructions on installing ruby on rails
on shared linux host. After uploading and uncompressing ruby 1.8.2, I
ran the configure script, and here is the output:

-jailshell-2.05b$ ./configure --prefix=/usr/local/ruby
–exec-prefix=/usr/local/ruby
checking build system type… i686-pc-linux-gnulibc1
checking host system type… i686-pc-linux-gnulibc1
checking target system type… i686-pc-linux-gnulibc1
checking for gcc… gcc
checking for C compiler default output file name… a.out
checking whether the C compiler works… yes
checking whether we are cross compiling… no
checking for suffix of executables…
checking for suffix of object files… o
checking whether we are using the GNU C compiler… yes
checking whether gcc accepts -g… yes
checking for gcc option to accept ANSI C… none needed
checking how to run the C preprocessor… /lib/cpp
configure: error: C preprocessor “/lib/cpp” fails sanity check

why am I getting this error?
any help appreciated.

Eugene wrote:

checking whether we are using the GNU C compiler… yes
checking whether gcc accepts -g… yes
checking for gcc option to accept ANSI C… none needed
checking how to run the C preprocessor… /lib/cpp
configure: error: C preprocessor “/lib/cpp” fails sanity check

please, help!